Is Less More?

Fueled by the barefoot-running craze and the success of the FiveFingers, a new crop of "minimalist" shoes has emerged, heating up the debate over what we should wear on our feet—and what the running shoe of the future will look like.

Call them what you like, toe shoes, foot gloves, gorilla feet. Call them strange-looking, weird, ugly if you're so inclined. Just understand that the funky, almost barefoot look of the FiveFingers hides from no one. The ultralight, increasingly chic shoe has made appearances this year at the Emmy Awards, on talk shows, and on the feet of everyone from Matthew McConaughey to former NFL star Eddie George. Whether actor Channing Tatum is rocking them on the streets of New York City or Google founder Sergey Brin is chatting up investors in them at corporate press conferences, the FiveFingers announce "I'm a free thinker" (though fashionista haters have charged that on ordinary mortals they cry out: "I'm going home alone tonight!"). The shoes, from Italian shoe company Vibram, sell for between $75 and $125—$35 for a knockoff version at a street vendor's booth.

In addition to their nonconformist currency in popular culture, the FiveFingers—which weigh all of 5.7 ounces and have a minuscule heel height of 7.2 millimeters—present a health and exercise message as well, as we've seen with a recent barefoot tutorial from Dr. Mehmet Oz. "The shoes were designed to not give too much cushioning," the ubiquitous doctor explained on his TV show, "but they allow you to run off the arches of your feet so you bounce." And Time, which named the FiveFingers one of the best inventions of 2007 (when hikers and boaters first latched on to them), points out that the shoes give you "the barefoot experience without putting your tender soles at risk."

For runners, though, the popularity of the FiveFingers has only intensified an ongoing conversation that kicked off in the spring of 2009 with the publication of Born to Run. The book, a New York Times best seller, reports on the Tarahumara Indians of northern Mexico who reportedly suffer fewer running injuries than North Americans do, even though many members frequently race ultralong distances in thin rubber sandals. Born to Run also presents reasons why barefoot advocates, such as author Christopher McDougall, believe that the best way to learn good running form is completely unshod, letting your feet and legs feel the subtle changes in impact so you can adjust your body to lessen that impact. Heavily cushioned treads, many of which dominate today's running-shoe market, don't allow for such an experience, the barefooters contend. "Sure," McDougall, himself an ultramarathoner, says, "I'll throw on a minimal shoe, but when I want to get back on track with my form, I have to be barefoot."

Buoyed by ideas presented in the book, the ranks of barefooters have grown, with a new organization, the Barefoot Runners Society, adding 700 members nationally in its first few months. But even the Barefooters point out that there are times when the foot needs some minimal protection from the elements. FiveFingers offer runners a way to guard their soles from sharp pebbles or ice chunks while allowing the foot to move almost as if it had no shoe on at all. And they're proving to be more than a protective trainer. In May, a 31-year-old California runner, Patrick Sweeney, won the Palos Verdes Marathon in a time of 2:37:14—with FiveFingers on his feet.

They're also proving to be more than a fad. Just ask Nike, New Balance, Saucony, and the other big boys of the multibilliondollar running-shoe business who have glimpsed the future of running shoes and are racing—get this—backward to catch up.

Turn back the clock to the early 1970s, a time of big hair, bell-bottom jeans...and waiflike running shoes epitomized by the Waffle Trainer, created when legendary University of Oregon coach Bill Bowerman famously used his wife's waffle iron to add a cushy tread to the bottom of a racing flat, making for a running shoe that was grippier on the road (and paving the way for the birth of Nike). In the ensuing years, though, shoe companies began to add more cushioning to their products. Many researchers believed then (and many still do) that runners needed cushioning, both in the forefoot and especially the heel, to absorb the shock from the road. But because the cushioning lifts the heel off the ground, additional hardware—such as medial posts and plastic shanks—were added to the midsole to provide stability and counter the effects of overpronation (the twisting that occurs when your ankle rolls too far inward). The result: the introduction of so-called stability and motion-control shoes, whose features can be seen in such popular models as Asics's 13-ounce Gel-Kayano and New Balance's 15-ounce 1012. "For the past 30 years, it has been bulk, bulk, bulk," says Ned Frederick, Ph.D., a biomechanics consultant for shoe companies. "People added more cushioning because we were competing for that soft ride that everyone was after."

But like hemlines, pocket handkerchiefs, and pleated pants, it seems running shoes—both in style and substance—are subject to consumers' changing demands. Fueled in part by the FiveFingers phenomenon, many shoe makers have begun to engineer minimalist models with new low-to-the-ground designs and ultralight materials that still provide cushioning while increasing flexibility (see "The Lowdown," page 80). Some of these new shoes have heel heights of just eight millimeters, compared to, say, the 38 millimeters of the Brooks Beast, a popular motion-control shoe. And more light, pliable, and lower-heeled shoes are coming. "Watch how minimal goes to a dozen brands in 2011," says Marshall Cohen, chief industry analyst for The NDP Group, a market research firm. "We're looking at point-of-sale data from the stores. In mid-2010, it was around two percent of sales for all running shoes. By next year, it could be double digit." (Still, while any shakeup in the $5 billion running-shoe market is news, the size of the "minimalist shoe" market is fairly small, no more than 10 percent of running shoes, according to Matt Powell, an analyst with SportsOneSource.)

What may be more resounding than revenue, though, is the role the shoes can play in helping defuse the perception that running-shoe makers sell only overbuilt, overcushioned footwear. "If you're making money from a puffy running shoe, and all of a sudden people are saying the product may not be good for you, you have to address that," says Greg Dutter, editorial director of the trade magazine Footwear Plus.

And yet beyond the bandwagon marketing of the current minimal trend, companies continue to invest a great deal into researching what runners really do need. Often, their research revolves around cushioning. Now, with the rage in lightweight shoes upon us, the question becomes, how low do you go?

Perhaps it has been years since you last ran barefoot—maybe you were chasing your kid along the beach or your dog in a grassy field after a summer picnic. But try it someday. What you'll likely notice is that with barefoot running, you tend to land on the whole foot instead of the heel (the more likely scenario when running on the road in a traditional running shoe). And without that well-cushioned shoe inducing you to extend your stride, you'll take shorter, more frequent steps and land much more softly. And you're less likely to develop tibial stress fractures, plantar fasciitis, and other injuries common to runners. Or so says Irene Davis.

Davis, who has a doctorate in biomechanics, says she was a fairly conventional physical therapist for most of her 20 years at the University of Delaware, recommending the usual array of orthotic supports and motion-control shoes to runners. But then she gradually began to see that subjects with a heavier heel-strike had more injuries and realized that this heel-strike was often associated with cushioned running shoes. On the other hand, Davis contends, bare feet and minimal shoes help runners strengthen their feet so that they can move in healthy ways. She likens traditional motion-control shoes to a plaster cast covering a broken foot: Sure, the cast will stabilize the area while bones heal, but it does little to strengthen key muscles or ligaments. In a similar way, the highly cushioned shoes may overprotect our feet, preventing their parts from strengthening naturally.

"You have to be willing to change your position," says Davis, who now helps patients transition to barefoot running and has converted herself, typically covering 20 miles a week without shoes. "We've been teaching people to land more softly, which basically ends up making them less of a rearfoot-striker. And if you look at barefooters, they don't land on their heels."

But isn't the cushioning in high-end shoes intended to minimize impact and protect the foot from injuries? You'd think so, says Daniel Lieberman, a professor of human evolutionary biology at Harvard University, but his research says the opposite. In tests he conducted in Kenya in 2009, Lieberman found that native runners who grew up running barefoot most often had a forefoot strike. More important, their magnitude of impact was a third of that of rearfoot-strikers in shoes—which means a gentler landing. But was it the shoes that caused the rearfoot striking? For the typical runner in the United States, the cause—and thus the harder impact—may just be the shoes. In an article in Nature he published with Davis last winter, Lieberman wrote that cushioned, high-heeled running shoes "make it easier for runners to land on their heels. Furthermore, many running shoes have arch supports and stiffened soles that may lead to weaker foot muscles, reducing arch strength."

So then, if all the widgets and gizmos intended to give our running shoes cushioning and stability—like the dual-density EVA foam and the urethane heel counters—are actually more trouble than they're worth, shouldn't we just remove the stuff? Not so fast, says another researcher, Darren Stefanyshyn, a biomechanics professor at the University of Calgary. Having consulted for shoe companies, Stefanyshyn knows both the science of feet and the practicalities of the business. He says most runners have been conditioned for years by running-shoe companies to believe that cushioning prevents injuries—and the runners are not likely to revert to a running flat from four decades ago. Stefanyshyn believes a better solution would be to develop a lightweight shoe with a lot less cushioning but one that lets the foot flex to meet the ground and manage impact. "Anytime you can put your body in control of its own movement, that's usually a positive," says Stefanyshyn, citing, for instance, the potential for injury prevention. "Both footwear and barefoot running have their drawbacks, but if we could somehow minimize the negative qualities of each, you'd have a winner."

Nike thought it had such a winner in 2004 when it launched the Free, the original minimal trainer. It came about when Nike designer Tobie Hatfield, a one-time nationally ranked pole-vaulter, met one of his idols, fabled college track-and-field coach Vin Lananna. The two got talking about Lananna's practice of incorporating barefoot sprints into his athletes' workouts. Hatfield asked the coach if he worried about the kids hurting their feet. Lananna told him that he was only nervous about runners who chose to run barefoot off campus where a bottle cap or sheet-metal screw could end a Division I career. The conversation prompted Hatfield to come up with something that would replicate running on grass, even in downtown Brooklyn or L.A.

Hatfield brought his idea—which would come to be known as the Free—to Nike senior biomechanics researcher Jeff Pisciotta. At the company's Beaverton, Oregon, headquarters, Pisciotta had more than a dozen prototypes developed to see if they could match the strike patterns of bare feet on grass. Various existing thin-soled concepts didn't work, because they didn't create the unique pressure distribution of bare feet on grass. Then designers applied a technique first used on Sperry boat shoes in the 1930s, when slits cut into the rubber called "sipes" promoted traction. Very deep sipes cut into the rubber produced a floppy, eight-ounce shoe as comfortable as a bedroom slipper, with a meshy upper and an incredibly flexible sole. For many runners Frees actually changed their running style away from the heel-strike.

But the prototypes also caused problems. With in-house testers, they taxed arches and tendons, which was good, but without caution, Nike's consumer market—the average Joes and Janes who want to rush out for a five-mile run after work—could get hurt. According to Pisciotta, muscles and other body tissues will eventually adapt, but if you push them too far too fast, they break down. To avoid this possibility, Nike marketed the Frees as a runner's supplementary shoe, one to throw in the gym bag for limited use each week, say, for short drills or cooldowns.

The Free drew favorable publicity and, with its assorted colors and unusual design, clicked as a fashion accessory. Nike has sold several million Frees since its debut. But according to retail shoe sellers, compared to other Nike models, the Free has never gained full acceptance with competitive recreational athletes. Hatfield, who prides himself on being the guy who lives to serve the athlete, looks almost hurt when pressed about sales at runner-centric stores. "I know there's a disconnect, and it befuddles me," he says. "When I talk to pro athletes, they get it. But the specialty stores are a challenge, and breaking the paradigm is tough. They've pushed stability for so long, it's ingrained."

Just look through the upcoming product catalogs of the top running-shoe companies to see how the FiveFingers and the Free have helped spur development of minimalist shoes. Case in point: Saucony's Kinvara, which debuted last summer and is as light as the Free but has additional structural elements built in: a stiff heel counter and a more rigid sole that makes the shoe an everyday trainer. "Five years ago, when minimalism became more popular with the Free, it was meant to be used two or three days per week," says Saucony's senior designer Chris Mahoney. "We're now starting to see shoes that aren't as extreme as that but are meant to log your weekly miles in."

Then there is New Balance, which has the NB Minimus due in February, promoted as offering a barefoot feel with strategic cushioning. Also in February, Merrell debuts its Barefoot Collection, with a sole built by Vibram and a barely-there upper. Meanwhile, Adidas is developing a fall 2011 addition to its AdiZero line for runners looking for a light, fast everyday shoe. And Nike is using lessons from the Free in its Lunar Eclipse, a lightweight, stability trainer (it, too, is scheduled to arrive in stores in February).

And yet, for all these new designs and offerings, each shoe maker has its own idea of what is minimal—with some even avoiding the rush to launch "minimalist" models. Take Asics, the makers of such favorites as the Kayano and Gel-DS Trainer. Instead of coming to market with its own "minimal shoe," the Japanese maker has tweaked its current crop. One stability favorite, the GT-2100 series, has lost almost two ounces over the course of a few updates. "Our shoes have become more flexible over the last several years, and we've moved away from highly structured shoes," says Simon Bartold, Asics international research coordinator.

What the shoe companies are realizing (along with many runners) is that minimal isn't a static concept; what's bare bones to one person might seem like way too much shoe to another. How do you know what's right for you? The answer may one day come from the University of Calgary's Human Performance Lab, run by Benno Nigg, who has created many of the innovations that now frame the debate about minimalist shoes.

The Performance Lab is something of a birthing room for new and unconventional product concepts. In the early 1980s, Nigg was working as a consultant for Nike on its line of tennis shoes. While there, he offered input on the need to add more structure to Air models because the much-lauded Air units created even more instability than traditional foam. "I pushed the cushioning trend as much as anyone," the broad-shouldered Nigg says in his Swiss accent. "And I take the blame for pronation devices as well."

Much of his current research, though, is focused on the "soft-tissue vibrations" in the body. Nigg argues that understanding vibrations—such as the ones that shoot through our legs when our feet whack the blacktop—is the key to performance and may even lead to injury prevention. Every runner has a unique frequency generated by their muscles, called a resonance frequency. It depends on the unique type and size of muscles in your legs. When the vibrations from running come close to a person's unique resonance frequency, you feel discomfort. To check the kind of vibrations in runners, Nigg tapes electrodes to their legs while they are running. These painless sensors measure tiny electrical currents the muscle cells make when activated. Using higher math formulas called wavelet filters, he gets a useful picture of which muscles are firing and when—and what type of shoe would be ideal for an individual.

Since 2000, Nigg has placed electrodes on more than 1,000 runners, most recruited from the University of Calgary's sports teams and running clubs in the area. Some were rail-thin distance runners, others had the muscular carriage of sprinters or soccer stars. The upshot? Nigg has found that some runners' bodies are in tune with firmer shoes because they provide a high-frequency signal to the body, and other runners are in tune with softer shoes, which provide a low-frequency signal. If a shoe hits your natural resonance frequency, you feel uncomfortable after a few miles—and if you persist in wearing it, your muscles become overworked trying to counteract the nettlesome signals.After explaining his research, Nigg sits down to draw his vision of the optimal shoe for the runner tuned to a minimal shoe. You might expect it to be something shockingly out of the blue—flying buttresses made of carbon-polymer or crash pads injected with flubberlike gel. But once he's through penciling in lines and arrows, his sketch looks, well, like a track spike. The future is a track spike?

"There's no cushioning on the forefoot. For function, it's unneeded," he says. "For comfort—eh, you put a little inside the shoe to distribute forces." With this prototype, Nigg is projecting out to a time when most shoes are ultralight. They do away with foam and instead use some kind of structural element to both cushion and stabilize. Ideally, they keep you running—and away from injuries.

Not far from where Benno Nigg is doing his research, Reed Ferber directs the Running Injury Clinic, an office full of physical therapists, biomechanists, pressure-sensitive treadmills, and motion-capture cameras. You can order up a gait analysis ($200) or shoe recommendation ($50). On an average day, Ferber, who is also a professor at the University of Calgary, sees about a dozen runners who come in looking for cures for everything from sore lower backs to inflammation of the tibialis posterior, a key stabilizing muscle inside the ankle. And with the changing shoe landscape, he wouldn't be surprised if a whole new range of injuries started to come through his front door. Why? Because already he's seen how new approaches to running—even ones with the best of intentions—can sideline a runner. Ferber says about 20 percent of his patients come in injured after attending a workshop on the Pose Method, or natural posture, or another coached running style. "It doesn't matter what the workshop is," he says. "It's just the fact that the person radically changed his mechanics overnight and got injured." With runners suddenly switching from double-digit-ounce rides to svelte numbers like the FiveFingers, an upturn in aches and injuries is likely. "An ordinary shoe—a neutral-cushioned shoe off the rack—has some stability component to it. If people are going to all of a sudden transition to a minimal shoe, they have to have sufficient strength and flexibility to allow that to occur," says Ferber. "If you just plop them in a minimal shoe, it may quickly lead to injury."

And that rub—between developing shoes to match a sudden market demand while not, well, crippling a customer base—has many of the large shoe companies chafing when it comes to bringing minimalist shoes to runners. Yes, it may be hard to stand idle when an out-of-nowhere company like Vibram blasts onto the scene and rocks the industry, and then makes no bones that it intends to remain a player. Vibram is expanding its product line, with some of the newer takes on the FiveFingers inching toward the more conventional world of running footwear. Many runners, who may have started with the bare-bones KSO model, have moved to the Bikila, which has a few millimeters of traditional running-shoe foam in the forefoot and heel. And next spring, a new Bikila model will arrive with—gasp!—shoelaces.

Still, while most mainstream footwear makers are sticking a toe into minimalism, they continue to test in order to minimize the possibility of injury that lightweight shoes could cause. As Asics's Bartold puts it, "Elite runners can get away with a whole lot less shoe. But for someone who gets out of the office chair after 10 years and decides he wants to get fit, I think to go to a less-structured shoe has got disaster written all over it."

As such, the current mandate at most of the major shoe companies is to stay in tune with today's minimalist trend while at the same time keeping an eye out for new technologies and materials that will provide an advantage, say, five years from now. At the New Balance Sports Research Lab, a $2 million facility in Lawrence, Massachusetts, that opened in 2009, researchers collect data on subjects who are running in a range of heel designs—from one with a 12-millimeter rise between the heel and the forefoot to shoes that are as flat as a board. Sean Murphy, New Balance's engineering manager of advanced products, has found that most runners adjust their footstrike pattern from a heel-strike to a midfoot-strike as the height differences are evened out. The upcoming NB Minimus line, for instance, has models with a mere four-millimeter difference between the forefoot and rearfoot.

New Balance is also looking for new materials—exotic foams and other synthetics—that could replicate the soft tissues in your heel (and which naturally provide good cushioning). Such a development, Murphy says, would shave off ounces from a shoe and still offer comfort. Asics's Bartold agrees that the body provides the best models. "The future is in the better understanding of how biological structures work, and replicating the properties of these structures in shoes," he says. "Tendons and ligaments are incredibly strong, and they have ways to store elastic energy and release it at the right time."

But the future of minimal shoes may not involve a foam pad underfoot at all. Biomechanist Stefanyshyn believes someone might soon develop a mechanical shoe, a legendary goal for many shoe designers. The idea is to rely on some kind of spring or metal device to provide cushioning and support while also getting the foot closer to the ground. "A lot of mass is in the midsole. If we can still provide the cushioning that people know and love with a structural element, then you can decrease mass," says Stefanyshyn.

More far-reaching research involves psychological and neurological studies to inform the design of new shoes. At New Balance, researchers are looking at the line between useful feedback from the road and actual discomfort. "How much pain is a good thing?" asks Murphy. "Is this sensory feedback that's telling me I need to slow down or avoid roots coming out of the ground? Or is this too much pain?"

Bartold predicts a day when adaptive shoes will subtly change such factors on the fly to accommodate body changes, citing features in current Asics models designed to protect women from injury during the 14th day of the ovulation cycle, when tendons get more stretchy. In contrast to minimal-shoe models that have decreased the heel height, this shoe increased the wedge to 13 millimeters to protect a woman's Achilles during that time in the cycle. If the shoe could automatically lower at other times, it might provide the best solution for the customer.

As with the concept cars shown at the Detroit auto show, the most innovative shoes on corporate drawing boards may never see the light of day. But prodded along by the FiveFingers, which make you look positively simian while actually being quite evolved, shoe companies will keep looking for the next big thing. For the average runner, the benefits of a lighter yet functional running shoe may be cost (ideally, without all the extra weight, your treads should cost less to make) and fewer injuries. But think what a minimal shoe might do for performance. Researchers have measured efficiency increases of several percentage points in some athletes between a light shoe and a heavy one. "It's important to have the lightest-weight shoe possible for a particular athlete," says Bartold. "Mass is all important to your oxygen uptake." More simply put: Carry less weight and you don't get as tired as quickly, and you may go faster. Consider a runner who has gotten used to a particular lightweight shoe. The improvements in race times could be astounding. For instance, move from a 12-ounce shoe to a 10-ounce shoe. Then attempt a marathon. If all goes well, the lighter shoes may save a couple of minutes over 26.2 miles.

So, for runners who have just missed a Boston qualifier, and are seeking a way to meet the elusive mark, the answer may be no farther than the bottom of their feetThe Lowdown

Best of the barely-there shoes

We tested the latest minimalist models at the RW Shoe Lab and on the feet of two dozen wear-testers. Seven pairs rose to the top due to their ultralight weight, flexibility, and low heel heights. In the reviews that follow, each shoe's flexibility and cushioning scores are compared to the average range of cushioning and flexibility scores for the running shoes we typically test. (Note: The average running shoe weighs 12 ounces and has a heel height of 36 millimeters.)

"Barefoot" Shoes

If you want to feel as if you're wearing (practically) nothing on your feet, these two shoes put little between you and the ground. Whether walking or running, they're excellent tools for strengthening your feet and legs.

VIBRAM FIVEFINGERS BIKILA5.7 oz / Heel Height: 7.2 mmThe first of Vibram's "toe shoes" designed from the ground up for running, the Bikila features a segmented outsole and a thin layer of padding that provides mild protection to high-impact areas. $100 vibram.com

TERRA PLANA EVO8.7 oz / Heel Height: 11.1 mmThe Evo uses thin, durable materials (such as nylon and rubber) to create a rugged, superflexible shoe that keeps the foot in close contact with the ground as long as possible. $160 terraplana.com

PERFORMANCE TRAINERSMore cushioned than racing flats and boasting features typically found in structured shoes, performance trainers are ideal for speedwork. Runners used to cushioned or stability shoes should transition easily to these treads.

NIKE FREE RUN+8.4 oz / Heel Height: 28.4 mm The latest update to the original minimal shoe has a Nike Plus socket, offset lacing, and a highly segmented outsole that allows the shoe to flex in any direction your foot wants to move. $85 nikerunning.com

SAUCONY KINVARA7.7 oz / Heel Height 28.7 mmThis stripped-down trainer is designed with just enough material to hold down and cushion the foot while providing a level landing that complements a midfoot-striking running style. $90 saucony.com

RACING FLATSWith a lower heel than everyday trainers, a thin, airy build, and little outsole tread, racing flats offer as much as you need for race day and nothing more. Runners not used to flats should ease them into their routine slowly.

MIZUNO WAVE UNIVERSE 33.7 oz / Heel Ht.: 16.8 mmThis extremely lightweight racer is popular in Japan (and with our testers) due to its stripped-down yet balanced design that harkens back to shoes worn during the first running boom. $120 mizuno.com

STEP DOWN: If you're used to a stability shoe, try a performance trainer before moving to a racing flat or barefoot shoe.MIX IT UP: Stick with your regular trainers for long runs and use your minimal shoes for shorter distances until you're used to training in them.DO STRIDES: Build up your foot strength by doing barefoot strides on grass and by walking in your minimal shoes.RUN SMART: Do a few miles at first and then build up the distance each week. A gradual transition should help keep you from getting injured.